1. Field of the Invention
The present invention relates to an in cell touch panel, more particularly, to an in cell touch panel with high resolution.
2. Description of Related Art
Displays with touch control functions are popularized nowadays. Typically a display realizes its touch control function by employing a touch panel whose working type may include resistance, capacitance, infrared ray, or surface acoustic wave.
FIG. 1 illustrates a display 16 employing an additional resistance type of touch panel 10, which comprises a polymer substrate 11, a glass substrate 12, two conductive circuits 13 whose surface coated with indium tin oxide (ITO) 14 respectively arranged on the conductive circuit and between the two substrates 11/12, and many spacers 15 arranged between the two ITO 14 coatings. As shown in FIG. 1, when the user presses the polymer substrate 11 at a position, the route resistance and the measured voltage will be changed; accordingly the touching position can be estimated.
The manufacturing processes of the resistance type of touch panel are simple; however, the additional touch panel may affect the optical performance and increase the manufacturing cost of the display. A so-called “In cell touch panel” is developed to overcome these problems because its structure can comply with the structure of the active matrix display so that the manufacturing steps can be reduced.
FIG. 2 shows a conventional in cell touch panel disclosed by Taiwan Patent Application No, 200729121. The in cell touch panel includes a thin-film transistor substrate 20, a color filter substrate 21, and a liquid crystal 22 arranged between the two substrates 20/21. In addition, a plurality of lower protrusions 23 and pixel components (not shown) such as gate lines, data lines, and thin film transistors are formed on the thin-film transistor substrate 20 and sensing lines 24 such as indium tin oxide (ITO) are formed on the lower protrusions 23. The lower protrusions 23 may be formed in a same manufacturing step with gate lines or data lines. In addition, black matrixes 25, color filters 26 are formed on the color filter substrate 21, upper protrusions 27 are formed on a portion of the black matrixes 25, and a common electrode 28 is formed to cover the color filters 26, the black matrixes 25, the upper protrusions 27, and the color filter substrate 21.
Accordingly, the upper protrusion 27, the common electrode 28, the lower protrusion 23, and the sensing line 24 construct a sensing element/unit. When the user presses the surface of the sensing element to make the common electrode 28 and the sensing line 24 in contact, the input voltage Vcom of the common electrode 28 can be readout via the sensing line 24 to a sensing signal processor (not shown); therefore the touch position can be estimated.
However, the number of the sensing lines must be increased if the resolution of the in cell touch panel are needed to be promoted. The layout area limits the number of the sensing lines, and the number of the processor or the pins of the sensing signal processor must be increased in response, resulting in high cost.
Therefore, it would be advantageous to provide an in cell touch panel with promoted resolution achieved under the low cost condition.